Energy in the form of electrical power is a natural resource that must be carefully monitored to determine if it is being effectively generated, distributed and utilized. Presently available devices for measuring the use of electrical power in the main comprise discrete analog transducers which convert ac voltage and current signals from a power system into dc output signals proportional to the true power on the system. Typical utility revenue kilowatt hour (KWH) meters measure power in an analog fashion.
Utilities frequently find it desirable to measure power coming out of a generation on going into a power station. Utilities need to know whether the current and voltage is within certain limits. It is desirable to continuously monitor these factors for statistical use in forecasting for future planning or immediate control of generators and power flows for greater efficiency and safety.
In industrial control applications, it is important to be able to continuously monitor the current and phase of the power into a machine which may vary with the machine load.
Commonly, such transducers measure, at most, the voltage, current, real power and reactive power. Each such transducer costs in the order of $200-$300. A separate transducer is required for each circuit being monitored. Where a number of circuits are being remotely monitored for computer processing and display, the individual transducers must be connected to a data logger or data acquisition device and suitably processed to interface with the computer.
Accordingly, a need exists for a versatile low-cost ac monitor of electrical parameters which can be conveniently interfaced with a computer and can be programmed to continuously monitor and calculate a variety of electrical power factors of a plurality of circuits.